PSC 1121 – Work and Conservation of Energy Examples
1. A lawnmower with a weight of 250 N is pushed across a level lawn for a distance of 12.0 meters with a horizontal force of 420 N. How much work was done on the box?
Answer: 5040 Nm
2. A 90 kg student climbs up a
3.0 m high ladder in a time of 5.12 seconds. How many
Answer: 527.3 W
3. A 250 kg elephant is raised a distance of 3.2 m above the zoo floor using a crane. What is the kinetic energy will the elephant have as if falls off of the crane and hits the floor?
Answer: 8000J
4. A book with a mass of 0.95 kg is held 10 m above the ground. How much potential energy is transformed into kinetic energy.
Answer: 95 J
5. A horizontal force of 2500 N is applied to a 1200 kg car causing it to move 750 m along a level surface. Calculate the work done?
Answer: 1875000 J
6. A 25.0 kg cart is pushed with a force of 995 N a distance of 18.3 meters as you move some dirt from the garden. How much work do you do on the cart?
Answer: 18208.5 J
7. A 680 kg tiger runs up a 5 m hill in 10 s.
a) How much potential energy does the tiger gain?
Answer: 34000 J
b) What is the power generated by the tiger?
Answer: 3400 W
8. A 0.28 kg golf ball is dropped from the top of a bridge which is 97 m above the ground.
a) What is the potential energy of the golf ball?
Answer: 271.6 J
b) What is the velocity of the golf ball just before it hits the ground?
Answer: 44.05 m/s